This invention relates to a process for purifying monoclonal antibodies. In one of its more particular aspects this invention relates to the purification of mammalian derived immunoglobulins.
With the discovery of techniques for the preparation of monoclonal antibodies derived from mammals, particularly mouse monoclonal antibodies, the need has arisen for purification of such monoclonal antibodies. Conventional purification techniques in which mixtures containing either polyclonal or monoclonal antibodies are passed through a suitable column to selectively adsorb the antibody from the mixture and the adsorbed antibody is later eluted from the column in purified form have been used for this purpose. However, the yield and purity of the isolated antibodies which can be obtained is limited by the lack of specificity of the column.
Previous processes for the purification of immunoglobulins, for example, suffered from the relatively low specificity of the adsorbent for the immunoglobulin. In one such process, various fractions of immunoglobulins from sera of different mammalian species were adsorbed upon protein A-Sepharose.RTM. adsorbents at pH 7 or higher and eluted at pH's ranging from pH 2.5 to pH 6.5. [R. Lindmark, K. Thoren-Tolling and J. Sjoquist, "Binding of Immunoglobulins to Protein A and Immunoglobulin Levels in Mammalian Sera," Journal of Immunological Methods, 62:1 (1983)]. It was also known that binding of mouse IgG to protein A-Sepharose.RTM. is pH sensitive and that optimum adsorption occurs using 0.1M sodium phosphate, pH 8.0 buffer. [P. L. Ey, S. J. Prowse and C. R. Jenkin, "Isolation of Pure IgG.sub.1, IgG.sub.2a and IgG.sub.2b Immunoglobulins From Mouse Serum Using Protein A-Sepharose," Immunochemistry, 15:429 (1978)].
Recently, efforts have been made to increase the recovery of various immunoglobulins using specially formulated buffers. ["Mouse Monoclonal IgG.sub.1, Purification with Affi-Gel.RTM. Protein A," Bulletin 1172, Bio-Rad Laboratories, Bio-Rad Chemical Division, Richmond, Calif. (1984)].
It would be desirable to provide a purification process which would result in still higher yields of immunoglobulins.
Accordingly, it is an object of the present invention to provide an improved process for the purification of monoclonal antibodies and particularly immunoglobulins obtained from mammals.
It is another object of the present invention to provide such a process which does not require additional purification steps.
Anbther object of the present invention is to provide a rapid, convenient and economically practical process for improving the yield of monoclonal or polyclonal antibody realized in the adsorption thereof.
Other objects and advantages of this invention will become apparent from the following detailed disclosure.